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No. 9 Mines suggested a permeability value of 19 gpd/ft2 and a storativity <br />value of 0,002 were realistic for the "E" and "P" seams. There are no water <br />supply wells completed in coal seams in the permit or adjacent area. <br />Ground waters within the Iles and Williams Fork Formations of the Mesa Verde <br />Group are predominantly calcium and sodium bicarbonate types. Water in <br />contact with coals, however, may be a calcium sulfate type and contain <br />fluoride, iron, manganese, selenium, and sulfate in excess of Public Health <br />Service drinking water standards (Bragden and Giles, 1977). Dissolved solids <br />concentrations of water within the Iles and Williams Fork Formations major - <br />sandstone members range from 105 mg/1 to 1260 mg/1 in the permit area. The <br />water contained in the coals and thin discontinuous sandstones of these <br />formations is generally of poorer quality. Because of this poor quality and <br />limited yield, the lenticular sandstones and coals are not significant sources <br />of ground water in the area. <br />Limited quantities of ground water have been obtained from the Lewis Shale, <br />but use of water from this formation is considered insignificant in the <br />basin. Where the Lewis Shale is present in the area, it acts more as an <br />impermeable confining layer to assist in creating artesian conditions within <br />the porous sandstones of the underlying Mesa Yerde Group. <br />The Yampa River alluvium and Williams Fork alluvium both contain ground <br />water, These alluvial bodies may store and release water used by the <br />overlying vegetation, and may sustain a component of baseflow to the <br />associated river systems. While these alluvial units may provide some local <br />recharge to bedrock aquifers, they are also at least seasonally recharged by <br />rock aquifers within the permit and adjacent areas. <br />Empire Energy Corporation has analyzed the quantity and quality of ground <br />water in the alluvium of the Yampa River and Williams Fork River. The results <br />of the alluvial well tests are contained in Exhibit 10. As a result of the <br />thin saturated thickness (5 to 10 feet) and low well yields (less than 5 gpm) <br />these wells were slug tested and analyzed by the Bower and Rice method, 1976. <br />Transmissivity values between 64 and 80 gpd/ft and permeability values between <br />11 and 75 gpd/f t2 were obtained for the Williams Fork alluvium. <br />Transmissivities between 200 and 1,900 gpd/ft were indicated by tests of the <br />Yampa River alluvium while permeability values ranged between 26 and 280 <br />gpd/ft2. The Yampa alluvium has considerably better hydraulic <br />characteristics than the Williams Fork alluvium but is still not considered a <br />significant loco] aquifer. <br />There are three monitoring wells in the permit area from which current water <br />level and water quality data are obtained for the Williams Fork alluvium. <br />These are wells AVF3, AYF5, and AVF6. Prior to the closing of the Eagle No. 9 <br />Mine in 1985, there were five monitoring wells for the Yampa River alluvium. <br />From the data supplied by the monitoring of these two alluvial bodies, water <br />levels can be seen to fluctuate seasonally. Hydrographs indicate the highest <br />water levels in the alluvia occur during the months of May to July coincident <br />with snow melt and the high river stages. Water quality in the alluvia is <br />variable, reflecting to some extent a low degree of interchange with the <br />associated river water. Ground water from the Yampa River alluvium is <br />primarily sodium sulfate type but contains significant quantities of calcium <br />and magnesium. Dissolved solids average 5,253 mg/1 with a recorded maximum of <br />-26- <br />